Restructuring and Related Charges - Activities in Restructuring Accrual (Detail) - USD ($) $ in Thousands		3 Months Ended		6 Months Ended
		Jun. 30, 2017	Jul. 01, 2016	Jun. 30, 2017	Jul. 01, 2016
Restructuring Reserve [Roll Forward]
Adjustments to restructuring provisions		$ 777	$ 1,903	$ 2,056	$ 4,515
Harmonic 2016 Restructuring Plan [Member]
Restructuring Reserve [Roll Forward]
Beginning Balance				13,544
Restructuring charges				2,798
Adjustments to restructuring provisions				44
Cash payments				(7,605)
Foreign exchange gain (loss)				628
Ending Balance		9,409		9,409
Restructuring Reserve, Current	[1]	(5,269)		(5,269)
Restructuring Reserve, Noncurrent	[1]	4,140		4,140
Harmonic 2016 Restructuring Plan [Member] | Facility Closing [Member]
Restructuring Reserve [Roll Forward]
Beginning Balance				2,375
Restructuring charges				48
Adjustments to restructuring provisions
Cash payments				(676)
Ending Balance		1,747		1,747
Restructuring Reserve, Current	[1]	(854)		(854)
Restructuring Reserve, Noncurrent	[1]	893		893
Harmonic 2016 Restructuring Plan [Member] | TVN Voluntary Departure Plan [Member]
Restructuring Reserve [Roll Forward]
Beginning Balance	[2]			9,650
Restructuring charges	[2]			1,777
Adjustments to restructuring provisions	[2]
Cash payments	[2]			(4,862)
Foreign exchange gain (loss)	[2]			597
Ending Balance	[2]	7,162		7,162
Restructuring Reserve, Current	[1],[2]	(3,915)		(3,915)
Restructuring Reserve, Noncurrent	[1],[2]	3,247		3,247
Harmonic 2016 Restructuring Plan [Member] | Employee Severance [Member]
Restructuring Reserve [Roll Forward]
Beginning Balance	[3]			1,519
Restructuring charges	[3]			973
Adjustments to restructuring provisions	[3]			44
Cash payments	[3]			(2,067)
Foreign exchange gain (loss)	[3]			31
Ending Balance	[3]	500		500
Restructuring Reserve, Current	[1],[3]	(500)		(500)
Restructuring Reserve, Noncurrent	[1],[3]	$ 0		$ 0

[1] The current portion and long-term portion of the restructuring liability are reported under “Accrued and other current liabilities” and “Other non-current liabilities”, respectively, on the Company’s Condensed Consolidated Balance Sheets.

[2] See discussion of the TVN VDP above for future estimated payments through 2020.

[3] The Company anticipates that the remaining severance and benefits accrual at June 30, 2017 will be fully paid in 2017.